<div ng-app="myapp">
    <div ng-controller="myctrl">
        数量：<input type="integer" min="0" ng-model="qty" required>
        单价：<input type="number" ng-model="cost" required>
        总计：{{qty * cost | currency}}
    </div>

</div>

<script>
    var app = angular.module("myapp",[]);
    app.controller("myctrl",['$scope',function($scope){
        $scope.qty = 1;
        $scope.cost = 2;
    }]);

</script>